Knife and method of making same



F. P. HAwKlNs KNIFE AND METHOD OF'- MAKING SAME Nov. 30, 1943.

Original Filed Jan. 1'6, 1942 lNvr-:NTOR

FRED P HAWKINS BY ATTORNEY Patented Nov. 30, 1943 KNIFE AND METHOD F MAKING' SAME Fred P. Hawkins, -Kckomm Ind., assignor to Iiaynes Stellite Company, a corporation of Inana Continuation of application Serial No. 426,954,

January 16, 1942. This application 6, 1,942, Serial No. 429,786

February a claims. (ci. 'ic- 101) The present invention relates to tools, and

' more especially to'large sharp edged tools, such as plowshares and power-driven knives, whose cutting edge comprises a hard-faced material that has been fusion-deposited to a base of tough but more readily abradablgmetal, to provide a hard, wear-resisting-core within a tough "supporting shell, This application is a continuan tion of my application Serial No. 426,954, filed method of producing the same; to provide in such a knife a better bond between the hard-metal insert and the tough base material; to provide a knife possessing improved self-sharpening characteristics; and to provide a knife, or` the like,v having uniform wearing qualities. other objects of the present invention will become more apparent from the following description and the accompanying drawing illustrating the invention as applied to a sugar-cane knife.

January 16, 1942. In the drawing,

The invention herein has been described with Fig. 1 is a side elevational View of a knife blank, special reference to a sugar-cane knife adaptedv recessed to receive a hard-metal deposit; to be mounted on al rotating shaft or drum, so Fig. 2 is. a side elevational view of the comthat the cutting action occurs with considerable pleted knife blade, ground and in condition for force or impact. It will'be apparent, however, 15 use; that the principles of the invention may be ap- Fig. 3 iS a bOiJtOm View 0f the knife ShOWn in plied to tools generally and especially to knives Fig. 2; or similar bladed implements whether of a ma- Fig. 4 is a' sectional view through the blade Achine or hand-operated type. blank on the line of 4-4 of Fig. 1;

In the handling of sugar cane, the stalks are 2o Fig. 5 is a sectional view through the completusually fed upon a moving belt to theA crushing ed blade taken on the line 5-5 OffFig. 2: and

ymills. To obtain the most efficient crushingac- Fig. 6 is a cross-sectional view through the tion, the stalks must be cut, split, and shredded, completed blade taken 'on the line 8 6 of Fig. 2. in such manner that they make a bed of substan- Generally speaking, the invention comprises a tially uniformthickness on the belt. A knife of knife formed of a blank of tough abradable metal the present design is especially useful inv thus such as mild steel, one edge of which is milled preparing the sugar-cane stalks for thecrushing or otherwise recessed to provide'an 'undercut poroperation. tion adapted to receive a hard-metal cre. The

Various attempts have been made to produce a recessed portion is filled by successively applysatisfactory knife for this purpose by uniting ing a `hard metal core, a thin bonding layer of hard wear-resisting metal and a shank or base of dense, tough metal, and a substantially -deep tough metal to form a composite blade especially layer of metal having the same general composidesigned for long useful life. The paramountl tion as the blank. objective in producing a sugar-cane knife is to More specifically the invention comprises an prepare a blade that will remain sharp throughimproved knife AK formed from a blank II of out the entire sugar-cane cutting period, consisttough abradable metal. The blank II may be ing of three to five months immediately followflame cut from a steel plate to the shape indiing the harvesting of a cane crop. Heretofore cated in Fig. 1 to provide a blade portioni! and such knives have proven unsuitable for one or a tang portion I3. The tang portion may be more reasons. In many cases. the hard-metal in- 40v provided with apertures I4 or othersimilar means sert has been silver-soldered or brazed to one by which the knife may -be firmly secured to a face of the base metal which has proven unsatsuitable holder, for example, to a rotatable disc isfactory since the blade has a tendency to peel or drum. The blank may be recessed along at apart at the joint. Other efforts to produce a least one side and adjoining end edge I6 thereof satisfactory knifev have resulted in chipping oli to provide an undercut portion l5 adapted to reof the hard-metal insert during continued use, ceive hard metal.` The undercut portion I5 exor wearing away of the blade at such a rapid rate tends inwardly from the edge I6 a greater disthat 4frequent shut-down was required in order tance at a region adjacent to the end of the knife to permit redressing the tools. than it does at the region adjacent to the tang:

Accordingly, the4 principal objects of the pres- 50 as indicated in Fig. 1, the undercut portion wident invention are: toprovide an improvedv cutens toward the end of the blade. By this arting tool that will remain .sharp throughout a rangement the hard-metal insert extends' to a longer period than heretofore has been possible; greater depth within the blade at the points of to` provide an improved sugar-cane knife and greatest wear, thereby compensating for nonuniform wear of the blade.

These and The blank II preferably comprises tough abradable steel, the composition of which may vary widely to suit individual requirements. 'I'he blank Il provides a-substantial support for the which the blade may be secured to a holder.

"Typical of such steels are the low and medium plain carbon steels of the types known as hotrolled steel, machinery steel and the softer grades of tool steel. These steels, while relatively soft withregard to wearing qualities, nevertheless are tough and resistant to shock, and in these respects form a very suitable backing for the more brittle hard-facing material inserted within the undercut portion I5. Harder steels may be used for the lblank where the impact is less severe, or the abrasion action greater.

A relatively thin layer or lamina of hard-facing material I1 is fusion-deposited on the base or bottom of the undercut portion I5. Although the composition of the hard-'facing material may vary widely, satisfactory results have been obtained by employing a, non-ferrous alloy including as its principal ingredients tungsten.. cobalt, and chromium, and generally known as Haynes Stellite alloy. Typical examples of Stellite compositions may be found in patents to Elwood Haynes Nos. 873,745; 1,057,423; 1,057,828; and 1,150,113. As another example, use may be made of an alloy containing chiefly iron, chromium,

and manganese, in the general proportions set naine onto the portion I5, which portion preferably has been preheated. The portion. I5 extends to a substantial depth into the plate or' blank Il, preferably to a depth slightly in excess of half the plate thickness, sothat the hardfacing material when applied forms aI layer substantially aligned with the central or median plane of the plate.

A relatively thin protecting and bonding layer I8 is then applied to the hard-facing material preferably by means of the oxy-acetylene flame, which flames allows the material to be spread on evenly and with no appreciable dilution of the layerll. The undercut portion I5 then may be completely filled to the original level of the plate with iiller metal I9 preferably having a composition of the same general type as that of the blank Il. For example, the layer I9 may comprise a plain low carbon steel 'of relatively high uidity such as standard coated plain steel rod which may be` deposited by the. arc-welding process.

It thus will be observed that the knife K comprises an extremely hard lamination I1 at the core which is highly resistant to wear. The hard layer is protected against chipping and cracking resulting from excessive impact by the adjoining protective layers of tough'steel. Since the base The function of the intermediate layer I8 is 1 in this fashion also results in less dilution of the hard layer when the heavy layer I9 is applied.

In the second place the layer I8 serves as a sort of tinning layer to provide a better bond between the hard layer i1 and the ller metal I9. This is important because the improved bond has been found to overcome the peeling action between the elements which was common in earlier designs.

The composition of the layer I8 may vary y i somewhat over a wide range but preferably consatisfactory for this purpose.

sists of a ferrous metal with good toughness and clean welding characteristics. `I have found that a low alloy steel containing about t4; chromium, about 1% manganese, and about 1A% silicon is 'Ihis particular metal has been found to provide excellent bonding characteristics lfor the layer I9. That is, by employing the layer I8, a better bond is provided than would be attained by depositing the layer I9 directly upon the hard-facing material. At the same time the layer I1 is better protected against the formation of surface checks and cracks which might otherwise serve as the starting point for subsequent chipping of the hard layer if the layer I8 were omitted. Y

Layers I 8 and i9 should be' similar enough in hardness and abrasion resistance that they will wear away at approximately the same rate as the metal i l comprising the body of the knife so that the beveled edges will wear substantially uniformly on opposite sides of the layer Il.

As a typical example, a knife has been produced according to the present invention from a steel plate approximately 6" x 2 0" in size. The endof the blade was flrst flame-cut about a 6"'radius andthe undercut portion I5 milled out as shown in Figs. 1 and a. The layer of hardfacing material then was deposited to a depth of not exceeding als after which the successive layers i8 and I9 were applied as previously indicated. The cutting edge was roughly beveled at a 15"y angle by the llame-cutting process after which th'e edge was hand lground to the iinal shape. Holes ll of approximately 1" in diameter then were drilled to provide means for con'- necting the knife to a handle or rotating holder.

The invention is susceptible of various changes without departing from the spirit of the invention or sacricing its advantages.

1. A severing knife comprising an abradable metal plate having a tang and a thin, wide, sub stantiallyfiat blade-portionthe edge of said blade portion being recessed to about one-half of the thickness of said plate and for a substantial part of its width inwardly: a thin substantially imperforate layer of hard-facing material Vfused. to and distributed over the bottom of such recessed portion in substantial alignment with the medium plane of said portion; a thin bonding layer of metal fused on top oi said hard-facing material:

and tough but relatively abradable flllermetal In this refused to said bonding layer and filling said recessed portion to the original surface level of said plate, both sides of the finished plate adjacent to 4the formerly recessed edge being adapted to be abraded off, to bevel the same, and thereby to expose said layer of hard-facing material as the cutting edge of the blade of said knife.

2. A severing knife blade comprising an 'elongated thin, wide, substantially flat plate of tough abradable steel, said plate being recessed in one face to a substantial depth and for a substantial part of its widthinwardly along the edge of one side and the adjoining end of said plate; a thin substantially imperforate layer of hard-facing material fused to' and distributed over the bottom of such recessed portion in substantial alignment with the median plane of said blade; and tough but relatively abradable filler metal fused to said layer of hard-facing material and substantially filling said recessed portion, both sides of,the finished plate adjacent to the formerly recessed edge being adapted to be abraded off. to bevel the same and thereby to expose said layer of hard-facing material as the cutting edge of the blade of said knife.

3. A severing knife comprising a tough abradable metal plate of elongated, thin, wide and substantially fiat shape, said plate being recessed inwardly for a substantial part of its width along at least one edge to form an undercut portion extending to a substantial depth in said plate, said undercut portion extending inwardly from said edge a greater distance at a zone near the end of said blade than at a zone remote fromvsaid end; a substantially imperforate lamina of hardfacing material fusion-deposited on said undercut portion in substantial alignment with the central plane of said plate; and a tough abradable metal layer fusion-deposited on said lamina and llingsaid undercut portion -to the original level of the surface of said platel both sides of said finished plate adjacent to the formerlyrecessed y edge being flame cut off to bevel the same and expose said lamina, and both sides of lsaid lamina positing hard-facing material in a thin even layer along said recessed zo'ne; protecting said material against dilution by depositing a thin layer of ferrous metal thereon" of a composition adapted to provide a good bond with' said hard-facing mate*- rial and building up said zone to substantially the original thickness of said plate by fusion de# positing additional ferrous metall on such protective layer.

.5. Ina method of making a knife from a ferrous metal plate,' the steps comprising undercutting said plate along at least one edgeof said plate to form a recessed zone extending about half-way through the thickness of said plate; depositing molten hard-facing material in a thin even layer along said recessed zone; fusion depositing on said material a thin protective layer of steel of a composition' adapted toprovide a good bond with said hard-facing material; and substantially completely filling said zone to the original thickness of said plate by fusion-depositing ferrous metal on said protective layer.

6. In a method of making a knife having a tang and an elongated blade, the steps compris,- ing milling the edge of said blade along a zone extending from the end thereof to a region adjacent to said tang, thereby to form an undercut portion along the edge of said blade, said undercut portion extending inwardly from said edge a lesserdistance at said region adjacent to said tang than at the region adjacent to said end; fusion-depositing a layer of hard-facing material along and within said undercut portion in a thin even layer; fusion depositing on said material a thin protective layer of steel of a composition adapted to provide a good bond with said hardfacing material; and substantially completely fillingsaid zone to the original thickness of said plate by fusion-depositing ferrous metal on said protective layer.

7. A method of preparing a knife-blade blank comprising undercutting a tough abradable plate of comparatively mild steel along one edge thereof; preheating said plate and fusion-depositing a lamina of hard-facing material onto such undercut portion; protecting said lamina by applying thereto with an Oxy-acetylene ame a thin layer of tough, dense steel such as carbon or low-alloy steel; and arc-welding'a relatively thick layer of comparatively mild steel to said thin layer, to build up said undercut portion to the original plate thickness.

8. In a method of making a knife, the steps comprising forming a shallow zone or groove in a ferrous metal plate along at least one edge of said plate to form a recessed zone extending about halfway through the thickness of said plate depositing hard-facing material in a thin even layer along said shallow zone; protecting said material against dilution by depositing a thin layer of ferrous metal thereon of a composition adapted to provide a good bond with said hard-'facing material; building up said zone to substantially the original thickness of said plate by fusion-depositing additional ferrous metal on such protective layer, flame cutting off both sides of said body adjacent to the hard-facing material to expose the same, and abrading off both sides of said hardfacing material at substantially the same angle to beveland sharpen said exposed edge to form the severing edge of said tool. l

FRED P. HAWKINS. 

